In this article, I will be explaining about the few concepts of Water Jet Machining (WJM) and Abrasive Water Jet Machining (AWJM) which you must know for GATE Exam. The Apparatus for WJM and AWJM were shown in the images below. You can collect the data from the Images and the rest theory was presented below. The points which are important are bolded in size so that you can easily take the information from this article.
Water Jet Machining Process(WJM):
- When very high-pressure water is passing through the convergent nozzle the pressure energy is converted into velocity energy or kinetic energy.
- Therefore the water is coming out from the nozzle at a very high velocity which is obtained to be 200 to 400 m per second.
- When this high-velocity water Jet is impinging onto the workpiece, the continuous impact load is acting onto it.
- Therefore very soft materials will experience plastic deformation and fracturing.
- From the above, the mechanism of material removal is due to plastic deformation and fracturing and also called an Etching process.
- In this, the Material Removal Rate(MRR) is directly proportional to the velocity of the water jet and this velocity depends on the distance between the nozzle tip and workpiece.
- In this, no tool is used and the only nozzle is used and to withstand higher pressures.
- The nozzle is made by using Tungsten Carbide.
10. Wear Ratio: Infinity.
Advantages of Water Jet Machining:
- Very soft materials like rubber can be easily machined
- No electrical conductivity of workpiece is required
- No thermal effects on the workpiece are required.
Limitations of Water Jet Machining:
- Pressurizing the water to very high pressure is difficult.
- This method can’t be used for machining of hard materials.
- Developed for cutting of very soft materials like rubber.
Applications of Water Jet Machining:
- It is used for machining or cutting reinforced plastic.
- Use to cut stone which can reduce the dust in the environment.
- It is used to cut hard metal like titanium, stainless steel, etc.
- It is used in aerospace industries.
- Used for machining PCB.
Abrasive Water Jet Machining Process(AWJM):
It is advanced of Water Jet Machining Process which includes Abrasives as a medium. The detailed explanation of Abrasive Water Jet Machining was presented below.
To overcome the second disadvantage of water jet machining, the abrasive particles will be added into the water so that the abrasive particles also comes out from the nozzle at very high velocity.
When these high-velocity Abrasive particles are impinging onto the hard work piece’s, it is possible to produce plastic deformation fracturing in the hard work materials also and this process is called as Abrasive water jet machining.
As the percentage of abrasives are increasing, the material removal also increases but the flow characteristics of the liquid mixture is coming down.
Therefore the optimum percentage of abrasives will be about 40 to 60%.
It is mainly developed for cutting of granite and marble of complex shapes.
Advantages of AWJM:
In most of the cases, no secondary finishing required
- No heat affected zone
- No cutter induced distortion
- Eliminates thermal distortion
- Low cutting forces on workpieces
- Localises structural changes
- No slag or cutting dross
- Limited tooling requirements
- Typical finish 125-250 microns
Limitations of AWJM:
- high capital cost and high noise levels during machining.
- It cannot cut the materials that degrade quickly with moisture.
- Surface finish loses at higher cut speeds.
Applications of AWJM:
It is highly used in the automotive, aerospace and electronics industries.
In aerospace industries, parts such as engine components (aluminum, titanium, and heat resistant alloys), aluminum body parts,titanium bodies for military aircraft, etc. are made using abrasive water jet Machining process.
This is the complete explanation about Abrasive Water Jet and Water Jet Machining Process in a detailed manner. These processes will come under Non-Traditional Machining Processes which carries 1 Mark for GATE Exam.
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